The present invention relates to a tire/wheel assembly and a run-flat support member, and more specifically to a tire/wheel assembly and a run-flat support member which enable an improvement of driving stability during run-flat traveling and a lightweight elastic ring.
In response to demands from the market, there have been many technologies proposed to allow a vehicle to run urgently for several hundreds of kilometers even when a pneumatic tire is punctured while the vehicle is running. Among these many proposals, technologies proposed in Japanese Patent Laid-Open Publication No. 10-297226 and Published Japanese Translation of a PCT Application No. 2001-519279 enable run-flat traveling by fitting a core onto a rim in the inner side of a cavity of a pneumatic tire that is assembled to the rim, and by supporting the punctured tire using the core.
The foregoing run-flat core (support member) includes a circular shell in which the outer circumferential side thereof serves as a support surface and the inner circumferential side thereof is opened so as to form two leg portions. Also, elastic rings are fitted to both leg portions of the circular shell, thus the run-flat core is supported on the rim through the elastic rings. By using this run-flat core, a conventional wheel and rim can be used as they are without any particular modifications. Therefore, the run-flat core is advantageously adopted without causing confusion in the market.
The elastic ring of the foregoing run-flat core is made of high hardness rubber that supports the weight of a vehicle body. However, the high hardness rubber is not capable of supporting the weight in a lateral direction sufficiently during run-flat traveling. Therefore, there has been a problem that driving stability cannot be improved enough. In addition, because the elastic rings support the weight of the vehicle body, it is required to design the rubber to have an enough thickness for enduring the weight, thus causing an increase in weight.